Just a small tweak

You are using `escape()` for encoding search terms, as it is seen in 

```
escape(document.getElementById("search_form_input").value)
```

It actually outputs ill-encoded strings for non-English terms. Also `escape()` is already depreciated. Using `encodeURIComponent()` instead will solve these problems.
Merge pull request #1 from robbielj/patch-1

Replace of escape() with encodeURIComponent().